OEFA said in a statement late Tuesday that it was still supervising operations at Cuajone but had ruled out any tailings spill.

On Sunday, OEFA had described a "greenish solution" flowing from the mine's installations into a local river and announced it was investigating a potential tailings spill.

Southern Copper, controlled by Grupo Mexico, had denied any tailings spill. However, it has said the rains caused flooding in some of its installations and one of its employees was swept away by a mudslide while working.

Tailings are the mud-like byproducts, including finely groundrock particles, left over from mining and extracting resources.

It suspended its concentrator plant at Cuajone on Friday and said on Monday it expects to fully restart it in coming days. (Reporting by Mitra Taj; Editing by Jeffrey Benkoe)